Method and System for Monitoring Networks with Variable, Virtual Service Rates

ABSTRACT

Embodiments of the invention are directed to a computer-implemented method for monitoring a computerized network comprising several nodes that are, each, configured for receiving and/or sending data packets via one or more communication channels, such that physical queues of data packets arriving at and/or departing from each of the nodes may form in said one or more communication channels. According to this method, virtual queues are maintained, wherein each of said virtual queues simulates a queue of data packets in a virtual channel associated to one of said one or more communication channels, wherein the service rate of said virtual channel can be varied. The virtual queues maintained are further monitored. Finally, this method comprises varying a service rate of one or more virtual channels, on which queues are respectively simulated by one or more of the virtual queues maintained.

BACKGROUND

The invention relates in general to the field of computer-implementedmethods and systems for monitoring data communication networks, inparticular for monitoring queues at switches or nodes of such networks.

The monitoring, control, management and optimization of large, networkedcomputerized systems (such as datacenters, high-performance computing(HPC) systems, clouds, and transport [street/rail] networks) is agrowing challenge, owing to the lack of (network) observability in suchsystems. Large networks are distributed and decentralized systems thatcomprise thousands to millions of physical and/or virtual queues, andcarry large numbers of packet-based flows.

In the example of a cloud, HPC or datacenter network (DCN), these queuesare interconnected in a topological graph, which typically is a k-aryn-tree such as fat-tree, Clos, dragonfly or a k-ary n-cube such as amesh or hypercube.

Such DCN and HPC fabrics may convey Tera to Peta packets of trafficacross millions of ephemeral (mice) and persistent (elephants) flows.Despite decades of research in communications and transport networks,the nature and characteristics of such traffic remain hard to observeand comprehend. Hence a reduced capacity to control, schedule andoptimize such networks. In particular, the direct observation ofmultitude of queues is not (or hardly) possible inside a large networksuch as a DCN, particularly at the temporal granularity of a few packets(nanosecond to microsecond scale).

A scheme for building a space-time correlated global sampling system fora multitude of queues has been introduced A. S. Anghel, R. Birke, and M.Gusat (“Scalable High Resolution Traffic Heatmaps: Coherent QueueVisualization for Datacenters”), TMA 2014.

SUMMARY

According to an embodiment, a computer-implemented method for monitoringa computerized network is provided, wherein said network comprisesseveral nodes that are, each, configured for receiving and/or sendingdata packets via one or more communication channels, such that physicalqueues of data packets arriving at and/or departing from each of thenodes may form in said one or more communication channels, the methodcomprising: maintaining virtual queues, wherein each of said virtualqueues simulates a queue of data packets in a virtual channel associatedto one of said one or more communication channels, wherein the servicerate of said virtual channel can be varied; monitoring the virtualqueues maintained; and while maintaining and monitoring said virtualqueues, varying a service rate of one or more virtual channels, on whichqueues are respectively simulated by one or more of the virtual queuesmaintained.

According to another embodiment, a computer program product formonitoring a computerized network is provided, wherein said networkcomprises several nodes that are, each, configured for receiving and/orsending data packets via one or more communication channels, such thatphysical queues of data packets arriving at and/or departing from eachof the nodes may form in said one or more communication channels, thecomputer program product comprising a computer readable storage mediumhaving program instructions embodied therewith, the program instructionsbeing executable by one or more processors of one or more entities, tocause an apparatus to perform: maintaining virtual queues, wherein eachof said virtual queues simulates a queue of data packets in a virtualchannel associated to one of said one or more communication channels,wherein the service rate of said virtual channel can be varied, asopposed to an actual service rate of the associated one of said one ormore communication channels; monitoring the virtual queues maintained;and while maintaining and monitoring said virtual queues, varying aservice rate of one or more virtual channels, on which queues arerespectively simulated by one or more of the virtual queues maintained.

According to another embodiment, a computerized system configured formonitoring a computerized network is provided, wherein said networkcomprises several nodes that are, each, configured for receiving and/orsending data packets via one or more communication channels, such thatphysical queues of data packets arriving at and/or departing from eachof the nodes may form in said one or more communication channels, thesystem comprising a monitoring unit connectable to said network toestablish data communication therewith, and wherein said monitoring unitis an electronic circuit or processing unit that is programmed,designed, adapted or configured to: maintain virtual queues, whereineach of said virtual queues simulates a queue of data packets in avirtual channel associated to one of said one or more communicationchannels, wherein the service rate of said virtual channel can bevaried, as opposed to an actual service rate of the associated one ofsaid one or more communication channels; monitor the virtual queuesmaintained; and while maintaining and monitoring said virtual queues,vary a service rate of one or more virtual channels, on which queues arerespectively simulated by one or more of the virtual queues maintained.

Computerized systems, methods, and computer program products embodyingthe present invention will now be described, by way of non-limitingexamples, and in reference to the accompanying drawings.

BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a flowchart illustrating high-level steps of a method formonitoring a computerized network, in accordance with exemplaryembodiments;

FIG. 2 is a flowchart illustrating high-level steps of a method forvarying a service rate of a virtual communication channel, in accordancewith exemplary embodiments;

FIG. 3 shows a folded topology representation of switches (networkingnodes) of a computerized network, in accordance with exemplaryembodiments;

FIGS. 4A-4C schematically illustrate the mapping of data samplesreceived from the switches onto a data structure (2D representation),according to an isomorphic transformation of a network topology of theswitches, in accordance with exemplary embodiments;

FIG. 5 illustrates data packets queuing in a given communicationchannel, as involved in embodiments;

FIG. 6 illustrates data packets queuing in a virtual channel,corresponding to the physical channel depicted in FIG. 5, but having aservice rate set to a higher value than the actual service rate of saidphysical channel, in accordance with exemplary embodiments; and

FIG. 7 schematically represents a general purpose computerized system(e.g., an external entity), communicating with switches of a network,and suited for implementing method steps in accordance with exemplaryembodiments.

The accompanying drawings show simplified representations of systems (orparts thereof) and computerized methods, as involved in embodiments.Similar or functionally similar elements in the figures have beenallocated the same numeral references, unless otherwise indicated.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

In reference to FIGS. 1, 5, 6 and 7, an aspect of the invention is firstdescribed, which concerns a computer-implemented method for monitoring acomputerized network 100. The network 100 comprises several nodes(labelled 0-11 in FIGS. 3, 4 and 7). Each of the nodes is configured forreceiving and/or sending data packets 21-23 via one or more (physical)communication channels, such that physical queues 20 of data packetsarriving at and/or departing from each of the nodes 10 may form incommunication channels between the nodes.

The monitoring basically revolves around three main steps: virtualqueues 20 a (FIG. 6) are maintained (step S10 in FIG. 1); the virtualqueues are monitored (step S20 in FIG. 1); and different controls arechanged (step S30 in FIG. 1). Each of said virtual queues simulates aqueue of data packets 21-22 in a virtual communication channel 30 a. Thelatter is associated to and can be compared with a physicalcommunication channel 30 of the network. However, and as one mayrealize, the service rate of such a virtual channel can be varied, asopposed to an actual service rate of a physical channel. The servicerate of a channel is synonymous with the channel capacity (also calledlink capacity of a channel), a link being synonymous with acommunication channel.

A virtual queue 20 a is for instance schematically depicted in FIG. 6,which represents a virtual channel 30 a in which data packets 21-22 areconveyed, so as to form a virtual queue 20 a during a given time t. Thesituation in FIG. 6 is very much comparable to that of FIG. 5, whichdepicts a physical channel 30, in which data packets 21-23 are conveyed,so as to form a physical queue 20 during that same period of time t.However, because the service rate of the virtual channel is artificiallymodified, the number of packets counted as packets queuing on thevirtual channel 30 a may differ from the actual number of packetscounted as part of the queue 20 on the physical channel 30. In theexample of FIGS. 5 and 6, it is assumed that the service rate of thevirtual channel 30 a is higher than the actual service rate of thephysical channel 30, such that less packets (i.e., 2 instead of 3) arecounted as part of the virtual queue 30 a during the time period t, inthis example. As the service rate is higher, the virtual queue indeedtends to be smaller than the physical queue. Namely, as packets enterand leave the queue (e.g., simultaneously in a FIFO order), a channelwith higher service rate tends to “empty” its queue faster and thus havea smaller queue occupancy.

For example, principles similar to the so-called “Adaptive VirtualQueue” (or AVQ) algorithm may be used, in order to maintain virtualqueues. E.g., data packets may be counted as they arrive at a node(i.e., as they are buffered in a real, physical queue), so as to updatea corresponding virtual queue to reflect the new arrival.

The virtual queues maintained are monitored S20, using any suitableautomatic method. The monitoring may be supervised by a human operator,if necessary, via a suitable graphical user interface (GUI).

Remarkably, the present method further provides an adjustable control,whereby the (virtual) service rate of one or more virtual channels 30 amay be varied S32, while maintaining S10 and monitoring S20 said virtualqueues. That is, an algorithm, or a human operator may vary the servicerate(s) of one or more virtual channels, i.e., the virtual links to/fromone or more of the nodes. For example, an operator may choose to varyuniformly the virtual service rates of all virtual channels, for whichvirtual queues are monitored, in a same extent. In variants, the virtualservice rates may be varied independently for each virtual channel, atleast in a certain extent, or for subsets thereof. The virtual channels30 a are channels on which queues of data packets are simulated by thevirtual queues 20 a as otherwise maintained S10 and monitored S20 by thepresent method.

Using virtual queues makes it possible to vary, i.e., both decrease andincrease, the service rate of the virtual queues, and notably withrespect to their associated physical queues. Indeed, a service rate of avirtual channel can be varied, as opposed to an actual maximal servicerate of the associated communication channel. This enables themonitoring method to speed-up and slow-down, respectively, the temporalevolution of the monitored data, e.g., the traffic matrices of interest.The virtual service rate accordingly provides a control option which maybe tuned, e.g., to anticipate potential hotspots, bottlenecks, etc., forexample to detect congestion before it actually occurs, or to solvealready identified issues.

Based on the above monitoring method, appropriate steps may then betaken to solve issues or prevent potential issues (e.g., congestion) tooccur, in the network, by way of automated (or partly automated)methods, which can be implemented complementary to the above monitoringmethod. Now, that virtual queues be monitored does not precludemonitoring actual queues forming in the physical communication channels.On the contrary, the actual queues shall preferably be monitored too, inaddition to (e.g., simultaneously with) monitoring the virtual queues.

Virtual queues simulate, or account for, queues of data packets invirtual communication channels, just like actual queues account forqueues of data packets in physical communication channels. Although theyare an artificial construct, virtual queues are not more artificial thanphysical queues; they are just the result of counting data packets in adifferent way. However, the virtual service rates can be artificiallyconstrained and, in the present context, even varied, contrary tophysical channels, whose service rates (also called link capacities) aredetermined by their design, the materials used to physically link thenodes, etc., as known per se.

Virtual queues as used herein compare to the concepts of shadow queuesor phantom queues as sometimes used in the literature. However,typically the service rates of the virtual channels are typically set toa value that is less than the actual service rate of the correspondingphysical communication channels. The service rates of virtual channelsare furthermore typically kept constant (and not varied), at least notas a control option for the purpose of monitoring network traffics.

The present methods may be implemented in a centralized way, at anentity (such as, for example, computerized unit 101 in FIG. 7) that isexternal to but in data communication with the nodes 0-11 of the network100. In variants, the present methods may be implemented in adistributed fashion, by part or all of the nodes 0-11 of the network 100and/or by several external entities, and according to any suited networkcommunication protocol.

In embodiments, the service rates of the virtual channels are varied S32within a restricted interval, e.g., an interval that is between 10% and400% of the actual service rate of the physical communication channels.Although larger intervals, e.g., between 1% and 1000%, may becontemplated, the narrower range (10-400%) turned out to be most usefulin practice, for the purpose of monitoring network traffics.

Varying the service rate of the virtual queues may be compared toactuating a diaphragm of a camera, to regulate the amount of light thatpasses through the lens. Similarly, varying the service rate of thevirtual channels impacts the flow of data packets conveyed in thevirtual channels.

In all cases, the service rates may be varied so as to reach a valuethat exceeds the actual, maximal service rate (i.e., 100%) of thecorresponding physical channels. In order to exceed the maximal servicerate (100%), one may for instance simulate an increase of the signalingspeed of the virtual channels, because mechanisms that solely act on theinterpacket gaps may only help in achieving 100% of the virtual linkcapacities, as explained below in detail.

In embodiments discussed below, other control mechanisms may beimplemented, in addition to varying the service rate of the virtualqueues. In particular, the present methods may further comprise varyingS34 cutoff occupancies as to a queue occupancy of one or more of thevirtual queues maintained, while maintaining S10 and monitoring S20 thevirtual queues.

In particular, one may vary S34 a lower cutoff occupancy, under which avirtual queue occupancy is considered to be zero (i.e., the queue isconsidered to be empty) by the computerized methods used for the purposeof monitoring the computerized network 100. In addition, one may varyS34 an upper cutoff occupancy, above which a queue occupancy isconsidered to be maximal.

As it may be realized, varying cutoff occupancies provides additionalcontrol as to the sensitivity of the monitoring methods and furtherallows to save computational resources otherwise required to simulate(or account for) the virtual queues. In embodiments, only the lowercutoff occupancy is varied, which allows to control the “noise” causedby data packets in virtual channels, in the low occupancy regime. Inother embodiments, only the upper cutoff occupancy is varied, tominimize computations. Varying both the lower and upper cutoffoccupancies makes it possible to control the dynamic range ofsignal-to-noise ratios and, in particular, to focus on trafficconditions of interest, e.g., a sub-critical regime, while monitoringthe network 100. Varying cutoff occupancies may be compared to varyingthe sensitivity of the medium (e.g., glass plates, films, or digitalsensors) used in photography.

In embodiments, another type of control may advantageously be used, inaddition to varying service rates and, if necessary, cutoff occupancies.Indeed, the present methods may further comprise varying S36 a fractionof the data packets arriving at and/or departing from the nodes, andwhich are to be sampled by the nodes. The fraction of the samplingpackets is varied while maintaining S10 and monitoring S20 the virtualqueues, for the purpose of monitoring the network 100.

This fraction may be varied in absolute time (i.e., as an inversefrequency of sampling) or as a percentage of arriving/departing packets.This fraction is typically in direct relation with the probability ofpacket sampling, which may be expressed either relatively as apercentage of the arrival events (e.g., 0.01% of the arrivals, i.e., 1out of 10 000 arrivals, will trigger a local sample). In variants, thisfraction is based on absolute time units, e.g., with respect to a localor a globally synchronized clock.

Different sampling mechanisms may be involved, which mechanisms areknown per se. Beyond the fraction of packets to be sampled, the samplingmechanisms may involve a number of parameters, for example: aminimal/maximal number of bytes to be sampled per packet sampled; typesof data to be sampled (or not to be sampled), etc.

The execution of the sampling mechanism at the nodes may be triggeredfrom the monitoring entity, such as computerized unit 101 in FIG. 7,e.g., by sending packets interpretable and/or executable by the nodes0-11, for each of said nodes to sample a queue of data packets queuingat said each of said nodes. Such packets may be sent through a data path40 of the network or through a control path 50 of the network. Sendingsuch data packets via the data path allows for both scalability andspeed, as opposed to using the control path. This way, the samplingmechanism can be globally started and/or stopped from the externalentity.

The external entity may for instance be hardware, i.e., a physicalmachine (e.g., a server, running the monitoring process), or software(e.g., a user application, implementing this monitoring process), ormore generally, a set of machines (physical and/or virtual), interactingso as to implement the monitoring process. The external entity may forinstance involve an operator, a user application, a monitoring entity,etc. The monitoring entity may also use the sampled data returned by thenodes to perform specific operations or analyses thereon.

The nodes may for example implement a QCN-type of protocol, allowingthem to sample the queues. The data sampled may, in particular, relateto queues of data to be processed, being processed or having beenprocessed (if the sampling is carried out after the nodes have processedthe data packets). The data sampled may most simply relate to thesize/occupancy of the queues, their evolution fill rate or any othertemporal derivative thereof. Queues are typically estimated based on therate of incoming packets (and the service rate) vs. processed/leavingpackets.

Note that not all the nodes of a network may be targeted by the presentmonitoring methods. Instead, present methods may be implemented for arestricted set of nodes which nonetheless still form a network asdefined above.

The collection of the samples may be performed in a distributed mannere.g., the nodes return the samples according to an IP address of theexternal entity (e.g., as included in the received execution packets oraccording to instruction specified in such a packet) or in a centralizedway (the nodes systematically return samples to a same recipient, suchas computerized unit 101 in the example of FIG. 7).

As one may realize, varying the fraction of the data packets to besampled at the nodes compares to varying the exposure time (shutter), inphotography. Now, just like photography relies on three pillars that arethe aperture, the sensitivity and the shutter speed, present methods mayinvolve mixing the three types of control discussed above. I.e., varyingthe service rate of virtual channels and the fraction of the datapackets to be sampled make it possible to regulate the flow of datapackets and the packets to be eventually sampled, just like adjustingthe aperture and shutter allows to adjust light coming into the camera.Still, varying the cutoff occupancies may impact the optimal (virtual)service rates and fractions of data packets to be sampled, just like theamount of light needed is determined by the sensitivity of the mediumused, in photography. Thus, in preferred embodiments, the three types ofcontrol discussed above (virtual service rates, fractions of packets tobe sampled and cutoff occupancies) are jointly or concurrently varied,for the purpose of monitoring the network. For example, an operator mayattempt to concurrently optimize such controls, via a user interface ofthe monitoring system, which includes a monitoring entity, as discussedlater in detail, in reference to FIG. 7.

Referring to FIG. 2, embodiments are now described, wherein the step ofvarying the virtual service rate (step S32) involves simulating avariation S54, S57 in the interpacket gaps, i.e., the gaps betweenpackets conveyed on the virtual channels. This can notably be achievedby simulating a flow control mechanism on the virtual channels. In suchcases, one simulates receiver nodes that impose S54, S57 the interpacketgap between packets sent by the transmitter nodes on the virtualchannels. In particular, a standard link-level flow control may besimulated. In variants, any other suitable Ethernet flow controlmechanism may be relied on, whereby receivers controls the transmitterinjection rate. In other variants, a direct control of the localtransmitters' rates may be simulated.

As one may realize, changing the interpacket gaps allows the servicerate to be varied between 0 and 100% of the associated physicalchannels, i.e., a zero interpacket gap may allow to exploit 100% of thelink capacity, in the best case. Thus, another mechanism is needed whereone wishes to increase S55 the virtual service rates, for them to exceed100% of the normal service rate of their associated physical channels,as illustrated at step S55 of FIG. 2.

In that respect, in embodiments, increasing S55 the virtual service rate(above the maximal link capacity) is achieved by simulating an increaseof the signaling speed of the virtual channels. As noted earlier, thisincrease will preferably be limited to 400% of the actual signalingspeed of the physical communication channels. In a real network, thesignaling speed may be modified by logically modifying and/or physicallymodifying the physical link. Each of these can be simulated to obtaincomparable effects in the virtual channels.

Note that the mechanisms evoked above (flow control, signaling speed)are mechanisms that impact the manner the data packets in virtualchannels are counted and accounted for. Such mechanisms can thus beregarded as simulations. However, they do not preclude the possibilityfor implementing comparable mechanisms in the physical communicationchannels, so as to modify physical properties and/or data communicationprotocols of the physical communication channels of the network. Yet,any actual modifications of the network may, in turn, be taken intoaccount by the present monitoring methods, as parameters for thesimulated, virtual queues.

In detail, the flowchart of FIG. 2 starts with monitoring instructionsto change the virtual service rates, as received from, e.g., a humanoperator or an automaton, step S50. Upon receiving such instructions,S51, the algorithm proceeds to:

-   -   If an increase of the virtual service rate is sought, step        S52/Yes:        -   Test whether the virtual service rate already exceeds the            maximal, physical service rate, S53; and            -   If so, instruct to further increase the signaling speed,                S55; or            -   If not, instruct to decrease the interpacket gap, S54,                e.g., using any suited link-level flow control                mechanism;    -   If on the contrary, a decrease of the virtual service rate is        sought, step S52 (No):        -   Test whether the virtual service rate still exceeds the            maximal, physical service rate, S56; and            -   If so, instruct to decrease the signaling speed, S58, or            -   If not, instruct to increase the interpacket gap, S57.

As seen, this algorithm favors a mechanism relying on interpacket gaps,whenever possible, to more closely reflect operation of a real network.However, other strategies can be contemplated. In addition, theflowchart of FIG. 2 assumes that virtual service rates are variedsimilarly for all virtual channels, for simplicity. However, it need notbe so, e.g., the service rates may be varied independently, in a certainextent, if necessary.

Referring now to FIGS. 3-4C, the present methods may, in embodiments,further comprise steps of dynamically interpreting outcomes of (i.e.,results as obtained from) the step of monitoring S20, to display S40images of quantities based on occupancies of said virtual queues, as forinstance schematically depicted in FIG. 4C. Such quantities may notablybe derived from the data collected from the nodes 0-11, by themonitoring entity.

In embodiments, this interpretation may involve an isomorphictransformation of the network topology of the nodes, to map suchquantities onto an array representing said virtual queues, so as toenable, e.g., time-synchronous snapshot images of the network. Thequantities of interest are typically mapped onto a multidimensionalarray or, more generally, a multi-dimensional data structure. Then, themulti-dimensional data structure may, if needed, be represented as a map(e.g., a heat map, as assumed in FIG. 4C, or a density plot or ageospatial map, etc.). Examples of suitable isomorphic transformationsare proposed in the paper “Scalable High Resolution Traffic Heatmaps:Coherent Queue Visualization for Datacenters”, cited in the backgroundsection.

In embodiments, the quantities at stake comprise occupancies of saidvirtual queues and gradients of said occupancies. Preferably, theoccupancies and gradients thereof are rendered by varying, in thedisplayed S40 images, and at each cell of the array, a brightness and acolor, respectively. Typically, the image synthesis involves an additivecomposition of one or more values. For example, in the QCN case, one mayencode a 16 bits occupancy as luminance/brightness and a 16 bitsoccupancy gradient velocity as color red/green/blue (not shown).

For example, FIG. 3 depicts a network 100 that comprises severalswitches 0-11 that are, each, configured for processing data 21-23queuing thereat (as otherwise illustrated in FIG. 5). More in detail,FIG. 3 illustrates a folded topology representation of an extendedgeneralized fat tree (hereafter XGFT), namely a XGFT(3;2,4,3;1,2,2),where links are bidirectional. Node levels start at 0 from bottom to top(L0 to L3). Nodes within a level start at 0 from left to right. Forsimplicity reasons, only the switch levels (L1, L2, L3) are shown. L0 ispopulated with 2 (nodes)·12 (L1-switches)=24 (nodes). One particularpath (from switch 4 on L1 to switch 0 on L1) is highlighted. The dashedlink represents the upstream queue of; e.g., port 0 at switch 2 on L2.

As illustrated in FIG. 4, the data samples collected by the entity maybe mapped onto a heat map and the latter displayed to a user, anoperator, etc., e.g., to enable time-synchronous snapshot images of theoccupancy of the switch queues in the network. A heat map represents a3D data structure as a structured image, where ‘pixels’ are color-coded,blackened, or otherwise patterned, and their intensity varied so as torender the occupancies of the virtual queues and gradients thereof.

The heatmaps can be used in a variety of manners from the networkoperator. As a visualization of the state of the network, they enablefast and easy detection of congestion. For example, detection ofanomalies and malfunctions of the network. Additionally, the heatmapscould be used to increase efficiency of the network, e.g., byredirecting traffic away from hotspots.

FIG. 4 illustrates a possible example of spatial mapping example.Intermediate FIGS. 4A and 4B show how the XGFT of FIG. 3 can be mappedonto the heat map of FIG. 4C.

FIG. 4A unfolds and rotates the topology of FIG. 3 by 90 degrees. In therepresentation of FIG. 4A, links are unidirectional: the traffic flowsfrom left to right. Each level corresponds to the up-/down-streamdirection. All figures (4A-4C) highlight the same exemplary path fromswitch 4 on L1 to switch 0 on L1. Similarly, the dashed link highlightsthe send queue(s) of port 0 at switch 2 of level 2 (L2). Each link levelin FIG. 4A corresponds to a column in FIGS. 4B and 4C. Each cell in acolumn represents (top-down) the output queues ordered by: (i) theswitch and (ii) the port within that switch. E.g., C3 shows thedownstream output queues of the L3 switches: 4 switches·3 ports·1queue=12 queues. Typical current switches have 1 to 4 hardware queuesper port, but for clarity a single queue per port is assumed in thisexample, although the one skilled in the art may easily generalize thisto several queues.

The mapping depicted in FIGS. 4A-4C is merely an illustrative,pedagogical example. In particular, the map of FIG. 4C representsblackened or patterned ‘pixels’ (rectangles), or cells, among blankcells, where the black/patterned cells vs. blank cells encode binaryinformation, i.e., a load is detected (black/patterned cells), or not(blank cells), amongst links whose service rate is varied, according tothe present methods. Yet, in real implementations, the occupancies andgradients of the queues shall preferably be rendered by modulating thebrightness and color of the cells, as mentioned earlier.

In addition, the mapping technique used in FIG. 4 is only one of manypossibilities to enable visual monitoring. Keeping in mind currentscreen resolutions and formats, one understand that hundreds tothousands of queues may be monitored, using an isomorphictransformation. However, automated analysis (e.g., as notably enabled byadvanced computer-aided analysis) shall preferably rely on data mappedon multidimensional arrays (gathering many parameters per queue perswitch, and if necessary per port).

Referring now to FIG. 7, and according to another aspect, the inventioncan also be embodied as a computerized system (e.g. computerized unit101) configured for monitoring a computerized network 100. According tothe example in FIG. 7, the network 100 comprises several nodes 0-11 thatare, each, configured for receiving and/or sending data packets 21-23via communication channels, as described earlier. The computerizedsystem comprises a monitoring unit, or monitoring entity, which isconnectable to the network 100, so as to establish data communicationtherewith. Technically, said monitoring unit is an electronic circuit ora processing unit that is programmed, designed, adapted or configured toperform steps such as described earlier in reference to FIGS. 1 and 2.Namely, the monitoring unit maintains and monitors virtual queues 20 a,and further proceeds to vary the service rate(s) of the virtual channels30 a, upon receiving instructions therefor, and according to principlesalready discussed earlier.

In embodiments, the computerized system further comprises a graphicaluser interface, or GUI. The monitoring unit may thus dynamicallyinterpret outcomes of the monitoring to display, via the GUI, images ofquantities based on occupancies of said virtual queues, as discussedearlier in reference to FIG. 4.

More generally, this computerized system can be suitably designed forimplementing embodiments of the present invention as described herein.In that respect, it can be appreciated that the methods described hereinare largely non-interactive and automated. In exemplary embodiments, themethods described herein can be implemented either in an interactive,partly-interactive or non-interactive system. The methods describedherein can be implemented in software (e.g., firmware), hardware, or acombination thereof. In exemplary embodiments, the methods describedherein are implemented in software, as an executable program, the latterexecuted by suitable digital processing devices. More generally,embodiments of the present invention can be implemented whereingeneral-purpose digital computers, such as personal computers,workstations, etc., are used.

For instance, the computerized unit 101 depicted in FIG. 7 is ageneral-purpose computer, and may be regarded as being, hosting orotherwise enabling the functionalities of an “external entity”, or“monitoring entity” as defined earlier. In exemplary embodiments, interms of hardware architecture, as shown in FIG. 7, the computerizedunit 101 includes a processor 105, memory 110 coupled to a memorycontroller 115, and one or more input and/or output (I/O) devices 145,150, 155 (or peripherals) that are communicatively coupled via a localinput/output controller 135. The input/output controller 135 can be, butis not limited to, one or more buses 140 or other wired or wirelessconnections, as is known in the art. The input/output controller 135 mayhave additional elements, which are omitted for simplicity, such ascontrollers, buffers (caches), drivers, repeaters, and receivers, toenable communications. Further, the local interface may include address,control, and/or data connections to enable appropriate communicationsamong the aforementioned components.

The processor 105 is a hardware device for executing software,particularly that stored in memory 110. The processor 105 can be anycustom made or commercially available processor, a central processingunit (CPU), an auxiliary processor among several processors associatedwith the computerized unit101, a semiconductor based microprocessor (inthe form of a microchip or chip set), or generally any device forexecuting software instructions.

The memory 110 can include any one or combination of volatile memoryelements (e.g., random access memory) and nonvolatile memory elements.Moreover, the memory 110 may incorporate electronic, magnetic, optical,and/or other types of storage media. Note that the memory 110 can have adistributed architecture, where various components are situated remotefrom one another, but can be accessed by the processor 105.

The software in memory 110 may include one or more separate programs,each of which comprises an ordered listing of executable instructionsfor implementing logical functions. In the example of FIG. 7, thesoftware in the memory 110 includes methods described herein inaccordance with exemplary embodiments and a suitable operating system(OS). The OS essentially controls the execution of other computerprograms and provides scheduling, input-output control, file and datamanagement, memory management, and communication control and relatedservices.

The methods described herein may be in the form of a source program,executable program (object code), script, or any other entity comprisinga set of instructions to be performed. When in a source program form,then the program needs to be translated via a compiler, assembler,interpreter, or the like, as known per se, which may or may not beincluded within the memory 110, so as to operate properly in connectionwith the OS. Furthermore, the methods can be written as an objectoriented programming language, which has classes of data and methods, ora procedure programming language, which has routines, subroutines,and/or functions.

Possibly, a conventional keyboard 150 and mouse 155 can be coupled tothe input/output controller 135. Other I/O devices 145-155 may includeother hardware devices.

In addition, the I/O devices 145-155 may further include devices thatcommunicate both inputs and outputs. The computerized unit 101 canfurther include a display controller 125 coupled to a display 130. Inexemplary embodiments, the computerized unit 101 can further include anetwork interface or transceiver 160 for coupling directly to thenetwork 100 or (as assumed in FIG. 7) to an intermediate network 165,and in turn communicate with switches 0-11 of the network 100.

The network 165 transmits and receives data between the computerizedunit 101 and the network 100. Each of the networks 100 and 165 maypossibly implemented in a wireless fashion, e.g., using wirelessprotocols and technologies, such as WiFi, WiMax, etc. The network 100 or165 may be a fixed wireless network, a wireless local area network(LAN), a wireless wide area network (WAN) a personal area network (PAN),a virtual private network (VPN), intranet or other suitable networksystem and includes equipment for receiving and transmitting signals.The network 100 or 165 can also be an IP-based network for communicationbetween the unit 101 and any external server, client and the like via abroadband connection. In exemplary embodiments, the network 100 or 165can be a managed IP network administered by a service provider. Besides,the network 100 is packet-switched network such as a LAN, WAN, Internetnetwork, etc. The network 165 is preferably a packet-switched networktoo.

If the computerized unit 101 is a PC, workstation, intelligent device orthe like, the software in the memory 110 may further include a basicinput output system (BIOS). The BIOS is stored in ROM so that the BIOScan be executed when the computer 101 is activated.

When the computerized unit 101 is in operation, the processor 105 isconfigured to execute software stored within the memory 110, tocommunicate data to and from the memory 110, and to generally controloperations of the computerized unit 101 pursuant to the software. Themethods described herein (in respect of the computerized unit101) andthe OS, in whole or in part are read by the processor 105, typicallybuffered within the processor 105, and then executed. When the entitymethods described herein (in respect of the computerized entity 101) areimplemented in software, the methods can be stored on any computerreadable medium, such as storage 120, for use by or in connection withany computer related system or method.

Next, according to another aspect, the invention can be embodied as acomputer program product for monitoring a computerized network such asdescribed above. The computer program product comprises a computerreadable storage medium having program instructions embodied therewith,wherein the program instructions are executable by one or moreprocessors of one or more entities (e.g. one or more computerized unit101) such as evoked above, to cause the one or more entities to performthe steps S10-S40, according to the present embodiments.

In embodiments, the program instructions are executable to further causethe one or more entities to vary S34 cutoff occupancies, whilemaintaining and monitoring S20 said virtual queues, according toprinciples described earlier. In addition, these program instructionsmay be executed to further cause the one or more entities to vary thefraction of arriving/departing data packets that are to be sampled bythe nodes and, this, while maintaining S10 and monitoring S20 thevirtual queues.

The computer readable storage medium can be a tangible device that canretain and store instructions for use by an instruction executiondevice. The computer readable storage medium may be, for example, but isnot limited to, an electronic storage device, a magnetic storage device,an optical storage device, an electromagnetic storage device, asemiconductor storage device, or any suitable combination of theforegoing. A non-exhaustive list of more specific examples of thecomputer readable storage medium includes the following: a portablecomputer diskette, a hard disk, a random access memory (RAM), aread-only memory (ROM), an erasable programmable read-only memory (EPROMor Flash memory), a static random access memory (SRAM), a portablecompact disc read-only memory (CD-ROM), a digital versatile disk (DVD),a memory stick, a floppy disk, a mechanically encoded device such aspunch-cards or raised structures in a groove having instructionsrecorded thereon, and any suitable combination of the foregoing. Acomputer readable storage medium, as used herein, is not to be construedas being transitory signals per se, such as radio waves or other freelypropagating electromagnetic waves, electromagnetic waves propagatingthrough a waveguide or other transmission media (e.g., light pulsespassing through a fiber-optic cable), or electrical signals transmittedthrough a wire.

According to an embodiment, a computer-implemented method for monitoringa computerized network is provided, wherein said network comprisesseveral nodes that are, each, configured for receiving and/or sendingdata packets via one or more (physical) communication channels, suchthat physical queues of data packets arriving at and/or departing fromeach of the nodes may form in said one or more communication channels.According to this method, virtual queues are maintained, wherein each ofsaid virtual queues simulates a queue of data packets in a virtualchannel associated to one of said one or more (physical) communicationchannels, wherein the service rate of said virtual channel can bevaried. The virtual queues maintained are further monitored. Finally,this method comprises varying a service rate of one or more virtualchannels, on which queues are respectively simulated by one or more ofthe virtual queues maintained.

The service rate may for instance be varied within an interval that isbetween 10% and 400% of the actual service rate of the one or morecommunication channels.

The service rate may notably be varied by simulating a variation ofinterpacket gaps between packets conveyed on said one or more virtualchannels, e.g., by simulating a flow control mechanism such as alink-level flow control mechanism.

Interestingly, the service rate may be increased to a value that islarger than the actual service rate of the one or more communicationchannels, e.g., by simulating an increase of a signaling speed of theone or more virtual channels.

In embodiments, the outcomes of the step of monitoring may bedynamically interpreted, to display images of quantities based onoccupancies of said virtual queues. This interpretation may for instancecomprise applying an isomorphic transformation of a network topology ofsaid nodes, to map said quantities onto an array representing saidvirtual queues. Said quantities typically comprise occupancies of thevirtual queues and gradients of said occupancies. Said occupancies andsaid gradients of occupancies may for instance be rendered by varying,in said images, and at each cell of said array, a brightness and acolor, respectively.

According to another embodiment, a computer program product formonitoring a computerized network such as described above is provided,wherein the computer program product comprises a computer readablestorage medium having program instructions embodied therewith, theprogram instructions being executable by one or more processors of oneor more entities, to cause an apparatus to implement steps according tothe above methods.

According to another embodiment, a computerized system is provided. Thelatter is configured for monitoring a computerized network such asabove. The system comprises a monitoring unit connectable to saidnetwork to establish data communication therewith. The monitoring unitis an electronic circuit or processing unit that is programmed,designed, adapted or configured to: maintaining virtual queues; monitorthe virtual queues maintained; and vary a service rate of one or morevirtual channels, according to principles discussed above.

In embodiments, the computerized system further comprises a graphicaluser interface, via which images of quantities based on occupancies ofsaid virtual queues can be displayed.

Computer readable program instructions described herein can bedownloaded to respective computing/processing devices from a computerreadable storage medium or to an external computer or external storagedevice via a network, for example, the Internet, a local area network, awide area network and/or a wireless network. The network may comprisecopper transmission cables, optical transmission fibers, wirelesstransmission, routers, firewalls, switches, gateway computers and/oredge servers. A network adapter card or network interface in eachcomputing/processing device receives computer readable programinstructions from the network and forwards the computer readable programinstructions for storage in a computer readable storage medium withinthe respective computing/processing device.

Computer readable program instructions for carrying out operations ofthe present invention may be assembler instructions,instruction-set-architecture (ISA) instructions, machine instructions,machine dependent instructions, microcode, firmware instructions,state-setting data, or either source code or object code written in anycombination of one or more programming languages, including an objectoriented programming language such as Smalltalk, C++ or the like, andconventional procedural programming languages, such as the C programminglanguage or similar programming languages. The computer readable programinstructions may execute entirely on the user's computer, partly on theuser's computer, as a stand-alone software package, partly on the user'scomputer and partly on a remote computer or entirely on the remotecomputer or server. In the latter scenario, the remote computer may beconnected to the user's computer through any type of network, includinga local area network (LAN) or a wide area network (WAN), or theconnection may be made to an external computer (for example, through theInternet using an Internet Service Provider). In some embodiments,electronic circuitry including, for example, programmable logiccircuitry, field-programmable gate arrays (FPGA), or programmable logicarrays (PLA) may execute the computer readable program instructions byutilizing state information of the computer readable programinstructions to personalize the electronic circuitry, in order toperform aspects of the present invention.

Aspects of the present invention are described herein with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems), and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer readable program instructions.

These computer readable program instructions may be provided to aprocessor of a general purpose computer, special purpose computer, orother programmable data processing apparatus to produce a machine, suchthat the instructions, which execute via the processor of the computeror other programmable data processing apparatus, create means forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks. These computer readable program instructionsmay also be stored in a computer readable storage medium that can directa computer, a programmable data processing apparatus, and/or otherdevices to function in a particular manner, such that the computerreadable storage medium having instructions stored therein comprises anarticle of manufacture including instructions which implement aspects ofthe function/act specified in the flowchart and/or block diagram blockor blocks.

The computer readable program instructions may also be loaded onto acomputer, other programmable data processing apparatus, or other deviceto cause a series of operational steps to be performed on the computer,other programmable apparatus or other device to produce a computerimplemented process, such that the instructions which execute on thecomputer, other programmable apparatus, or other device implement thefunctions/acts specified in the flowchart and/or block diagram block orblocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof instructions, which comprises one or more executable instructions forimplementing the specified logical function(s). In some alternativeimplementations, the functions noted in the block may occur out of theorder noted in the figures. For example, two blocks shown in successionmay, in fact, be executed substantially concurrently, or the blocks maysometimes be executed in the reverse order, depending upon thefunctionality involved. It will also be noted that each block of theblock diagrams and/or flowchart illustration, and combinations of blocksin the block diagrams and/or flowchart illustration, can be implementedby special purpose hardware-based systems that perform the specifiedfunctions or acts or carry out combinations of special purpose hardwareand computer instructions.

While the present invention has been described with reference to alimited number of embodiments, variants and the accompanying drawings,it will be understood by those skilled in the art that various changesmay be made and equivalents may be substituted without departing fromthe scope of the present invention. In particular, a feature(device-like or method-like) recited in a given embodiment, variant orshown in a drawing may be combined with or replace another feature inanother embodiment, variant or drawing, without departing from the scopeof the present invention. Various combinations of the features describedin respect of any of the above embodiments or variants may accordinglybe contemplated, that remain within the scope of the appended claims. Inaddition, many minor modifications may be made to adapt a particularsituation or material to the teachings of the present invention withoutdeparting from its scope. Therefore, it is intended that the presentinvention not be limited to the particular embodiments disclosed, butthat the present invention will include all embodiments falling withinthe scope of the appended claims. In addition, many other variants thanexplicitly touched above can be contemplated.

What is claimed is:
 1. A computer-implemented method for monitoring acomputerized network, wherein said network comprises several nodes thatare, each, configured for receiving and/or sending data packets via oneor more communication channels, such that physical queues of datapackets arriving at and/or departing from each of the nodes may form insaid one or more communication channels, the method comprising:maintaining virtual queues, wherein each of said virtual queuessimulates a queue of data packets in a virtual channel associated to oneof said one or more communication channels, wherein the service rate ofsaid virtual channel can be varied; monitoring the virtual queuesmaintained; and while maintaining and monitoring said virtual queues,varying a service rate of one or more virtual channels, on which queuesare respectively simulated by one or more of the virtual queuesmaintained.
 2. The method of claim 1, wherein said service rate isvaried within an interval that is between 10% and 400% of the actualservice rate of said one or more communication channels.
 3. The methodof claim 1, wherein the method further comprises, while maintaining andmonitoring said virtual queues: varying a lower cutoff occupancy as to aqueue occupancy of one or more of the virtual queues maintained, underwhich lower cutoff occupancy said virtual queue occupancy is consideredto be zero by a computerized method used by said computer-implementedmethod for the purpose of monitoring said computerized network.
 4. Themethod of claim 3, wherein the method further comprises, whilemaintaining and monitoring said virtual queues: varying an upper cutoffoccupancy as to said queue occupancy, above which upper cutoff occupancysaid queue occupancy is considered to be maximal by said computerizedmethod for the purpose of monitoring said computerized network.
 5. Themethod of claim 1, wherein the method further comprises, whilemaintaining and monitoring said virtual queues: varying a fraction ofthe data packets arriving at and/or departing from one or more of saidnodes, which are to be sampled by said one or more of said nodes.
 6. Themethod of claim 1, wherein varying said service rate is performed bysimulating a variation of interpacket gaps between packets conveyed onsaid one or more virtual channels.
 7. The method of claim 6, whereinvarying interpacket gaps is performed by simulating a flow controlmechanism on said one or more virtual channels, whereby receiver nodesimpose an interpacket gap between packets sent by transmitter nodes onsaid one or more virtual channels.
 8. The method of claim 7, wherein theflow control mechanism simulated is a link-level flow control mechanism.9. The method of claim 1, wherein varying said service rate comprisesincreasing said service rate to a value larger than the actual servicerate of said one or more communication channels.
 10. The method of claim9, wherein increasing said service rate comprises simulating an increaseof a signaling speed of said one or more virtual channels.
 11. Themethod of claim 1, further comprising dynamically interpreting outcomesof the step of monitoring of said virtual queues, to display images ofquantities based on occupancies of said virtual queues.
 12. The methodaccording to claim 11, wherein interpreting outcomes of the step ofmonitoring of said virtual queues comprises applying an isomorphictransformation of a network topology of said nodes, to map saidquantities onto an array representing said virtual queues.
 13. Themethod of claim 12, wherein said quantities comprise occupancies of saidvirtual queues and gradients of said occupancies.
 14. The method ofclaim 13, wherein said occupancies and said gradients of occupancies arerendered by varying, in said images, and at each cell of said array, abrightness and a color, respectively.
 15. The method of claim 1, furthercomprising monitoring said physical queues, while maintaining andmonitoring said virtual queues.
 16. A computer program product formonitoring a computerized network, wherein said network comprisesseveral nodes that are, each, configured for receiving and/or sendingdata packets via one or more communication channels, such that physicalqueues of data packets arriving at and/or departing from each of thenodes may form in said one or more communication channels, the computerprogram product comprising a computer readable storage medium havingprogram instructions embodied therewith, the program instructions beingexecutable by one or more processors of one or more entities, to causean apparatus to maintaining virtual queues, wherein each of said virtualqueues simulates a queue of data packets in a virtual channel associatedto one of said one or more communication channels, wherein the servicerate of said virtual channel can be varied, as opposed to an actualservice rate of the associated one of said one or more communicationchannels; monitoring the virtual queues maintained; and whilemaintaining and monitoring said virtual queues, varying a service rateof one or more virtual channels, on which queues are respectivelysimulated by one or more of the virtual queues maintained.
 17. Thecomputer program product according to claim 16, wherein the programinstructions are executable by one or more processors of one or moreentities, to further cause to vary, while maintaining and monitoringsaid virtual queues, a lower cutoff occupancy as to a queue occupancy ofone or more of the virtual queues maintained, under which lower cutoffoccupancy said virtual queue occupancy is considered to be zero by acomputerized method used by said computer-implemented method for thepurpose of monitoring said computerized network, and to vary an uppercutoff occupancy as to said queue occupancy, above which upper cutoffoccupancy said queue occupancy is considered to be maximal by saidcomputerized method for the purpose of monitoring said computerizednetwork.
 18. The computer program product according to claim 16, whereinthe program instructions are executable by one or more processors of oneor more entities, to further cause to vary, while maintaining andmonitoring said virtual queues, a fraction of data packets arriving atand/or departing from one or more of said nodes and which are to besampled by said one or more of said nodes.
 19. A computerized systemconfigured for monitoring a computerized network, wherein said networkcomprises several nodes that are, each, configured for receiving and/orsending data packets via one or more communication channels, such thatphysical queues of data packets arriving at and/or departing from eachof the nodes may form in said one or more communication channels, thesystem comprising a monitoring unit connectable to said network toestablish data communication therewith, and wherein said monitoring unitis an electronic circuit or processing unit that is programmed,designed, adapted or configured to: maintain virtual queues, whereineach of said virtual queues simulates a queue of data packets in avirtual channel associated to one of said one or more communicationchannels, wherein the service rate of said virtual channel can bevaried, as opposed to an actual service rate of the associated one ofsaid one or more communication channels; monitor the virtual queuesmaintained; and while maintaining and monitoring said virtual queues,vary a service rate of one or more virtual channels, on which queues arerespectively simulated by one or more of the virtual queues maintained.20. The computerized system of claim 17, wherein the system furthercomprises a graphical user interface, and said electronic circuit orprocessing unit is further programmed, designed, adapted or configuredto dynamically interpret outcomes of monitoring said virtual queues, todisplay, via said graphical user interface, images of quantities basedon occupancies of said virtual queues.